Japan will work to strengthen its defense and diplomatic capabilities to maintain peace, Prime Minister Kishida Fumio said on Saturday, according to public broadcaster NHK, adding that military buildups around the country have been growing.

Japan is a close ally of the United States and has condemned Russia's invasion of Ukraine, supporting Kyiv financially and joining international sanctions on Moscow.

"Military buildup, including nuclear and missile development, has been accelerating in areas surrounding Japan, and attempts to unilaterally change the status quo by force are growing," Kishida told a graduation ceremony at the National Defence Academy in Yokosuka near Tokyo, according to NHK.

He added that Japan faces "the most complex and challenging" security environment since World War Two, and the government will strengthen its defense and diplomatic capabilities to maintain peace and prevent security emergencies.

Kishida and US President Joe Biden will hold a summit on April 10 in the United States to boost the longstanding bilateral security alliance. 

The summit will take place in the face of growing Chinese influence and North Korea's continued military tests.